Teenagers in the study with all three negative lifestyle factors had a more than threefold greater likelihood of having frequent, severe headaches than normal-weight, active teens who did not smoke.

Headaches are a common complaint among teenagers, with 5% of teenage boys and almost 8% of teenage girls in one nationwide study reporting frequent migraines. In another study of older teens in Poland, 28% reported having had a migraine headache.

While obesity, smoking, and other lifestyle factors have been shown to influence the frequency and severity of chronic headaches in adults, the new study, published in the journal Neurology, is among the first to explore the relationship in teenagers.

Obesity, Smoking, and Headaches

The study is the first to examine the individual impact of specific negative lifestyle factors like obesity and smoking, says study researcher John-Anker Zwart, MD, PhD, of the University of Oslo.

"We were surprised by how many teenagers with headaches smoked or were overweight or physically inactive," Zwart tells WebMD. "We were also surprised that the impact of these negative lifestyle factors seemed to add up."

The research included almost 6,000 students in Norway between the ages of 13 and 18 interviewed about their recent headache history. They also were asked if they smoked and how much they exercised.

Roughly one in five teens (19%) said they were smokers, 16% were overweight, and 31% reported exercising less than twice a week.

Overall, about a third of the girls (36%) and one-fifth of the boys (21%) reported having recurrent headaches within the past year.

More than half (55%) of the overweight, sedentary teens who smoked reported recent frequent headaches, compared to one in four teens with none of these lifestyle factors.

Compared to normal-weight, active, nonsmoking teens, overweight teens, and teens who smoked were 40% and 50%, respectively, more likely to have frequent headaches. Exercising less than twice a week was associated with a 20% increase in the likelihood of frequent headaches.

It is not clear from the research if the negative lifestyle factors caused the frequent headaches or if they act more as triggers in already vulnerable teens.

Start of School Year Is a Vulnerable Time

Adolescent headache specialist Andrew D. Hershey, MD, PhD, tells WebMD that most children and teens with migraines and other severe, chronic headaches are genetically predisposed to have them.

"The two most common triggers for headaches in kids is skipping meals and not getting enough sleep," he says.

That makes the start of a new school year a particularly vulnerable time for junior high and high school students because their natural sleep cycle is often disturbed.

Around the time of puberty, adolescents develop a sleep phase delay that makes it natural for them to fall asleep later in the evening and wake up later in the morning.

"Most teens have to get up at 6:00 or 6:30 to get to school and many skip breakfast to get a little more sleep," he says. "That is two strikes against them before the day even gets started. Every year around the end of September and early October we see a big increase in headache cases."